If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

THS4513-SP: Absolute maximum input power / maximum input voltage swing

Part Number: THS4513-SP

I am an engineer at Airbus DS and we are using the THS4513-SP within one in our design. In more detail it is driving an ADC. The ADC applies the CM voltage (1.5V) to the THS4513-SP. The amplifier circuitry is as described in the datasheet. Furthermore the THS4513-SP is supplied with 0V and 3.3V. The amplifier input is fed by a 50ohm source. Nominal the 50ohm source feeds the amplifier with a signal power of -3dBm. Anyway, the application shows that in some cases, power levels of 17dBm could be fed to the amplifier. When I studied the datasheet in order to find out which input power levels can be handled by the amplifier the following information I have found:

ABSOLUTE MAXIMUM RATINGS

 ... ... ... VI Input voltage ±VS ... ... ..

When I do understand the information correctly, the maximum input power level of the amplifier is as follows:

Assuming a sin-input voltage, the max. allowed sin- input voltage is oscillating between 0V and 3.3V which means in this application:

In_max_V = 1.5V + 1.5V*sin(2*Pi*f*t ) [volts]

Because the input impedance of the amplifier circutry is almost 50ohm, this would result into a maximum input power coming from a 50ohm source of:

In_max_P = 10 + 20*Log(Vpeak) = 10 + 20*Log(1.5V) = 13.522 dBm

Is my understanding correct?

Best Regards,

Daniel Popken

• Hi Daniel,

This is a high-input-impedance operational amplifier, with a differential input impedance of 1.67MEG and a common mode input impedance of 1.2MEG

The maximum input voltage is the supplies, and the maximum differential input voltage is 4V.

The device will not accept an input power waveform the way you are describing.

Best,
Sam